\documentclass{standalone}
\usepackage[scaled=0.95]{helvet}  % Load Helvetica font, slightly scaled for better appearance
\usepackage[T1]{fontenc}         % Ensure proper font encoding
\renewcommand{\familydefault}{\sfdefault}  % Set Helvetica as the default font

\usepackage[table,xcdraw]{xcolor} % Lädt xcolor mit der table-Option
\usepackage{colortbl}             % Für den \rowcolor Befehl


\begin{document}
\begin{tabular}{|l|}
    \hline
    \multicolumn{1}{|c|}{\cellcolor[HTML]{C0C0C0} \textbf{Klasse}} \\
    \textit{\underline{Klassen ID}} \\ \hline
    aW\_24-28\\
    bW\_24-28\\
    cW\_24-28\\
    dP\_24-28\\
    eW\_24-28\\
    fP\_24-28\\
    \hline
    \end{tabular}
\end{document}